A French psychologist known for creating the first IQ tests, focusing on identifying students with special needs and pursuing interests ranging from law to physiology.

A French surgeon and anthropologist recognized for identifying connections between specific brain regions and functions, notably researching skull measurements to study human races.

An English educational psychologist noted for his work in statistical analysis and factor analysis, later revealed to have falsified data supporting theories of inherited intelligence.

An American psychologist who introduced IQ testing in America, which was used to identify intellectually disabled people and argued for limiting their ability to have children.

An Italian criminologist who developed a taxonomy of physical traits to identify potential criminal behavior, popularizing hereditary theories in the late 19th century.

An American naturalist known for his collection of skulls used to measure cranial capacity, providing data to support polygenist beliefs in separate human species.

An English psychologist who developed multivariable factor analysis and theorized a general intelligence factor, contributing to the development of youth intelligence assessments.

An American psychologist who revised the Binet-Simon IQ scale, creating the Stanford-Binet scale, and was involved with a eugenicist group advocating for sterilization.

An American psychologist who pioneered psychometrics and developed new methods for intelligence testing, establishing the University of Chicago's Psychometric Laboratory.

An American psychologist and primatologist known for leading the development of the Army Alpha and Beta intelligence tests during World War I, with studies on primate behavior.